Date(s) - 09/14/2017
Science Center Room 4102
Jonathan Nichols of Lamont-Doherty Earth Observatory of Columbia University presents on “Northern Peatlands and the Hyperactive Holocene Carbon Cycle”. Light Reception to Follow!
Northern peatlands are vital the global carbon cycle. Using a new algorithm for calculating peat carbon accumulation, we show that there is nearly twice as much peat in the Northern Hemisphere as was previously calculated. This has a profound impact on our understanding of the carbon cycle during the Holocene. Previous attempts to estimate global peatland carbon accumulation rates were limited to data from peatlands with robust radiocarbon age models covering the entire Holocene and Late Glacial periods. This stringent data policy eliminated large amounts of otherwise legitimate radiocarbon measurements. With an expanded dataset, we have extended our record of northern peatland accumulation rates back to 22 ka, covering the important deglacial period. We also increased temporal resolution, uncovering new details, such as high rates of carbon accumulation during the Allerød warm interval. We also find a previously unreported increase in peat carbon accumulation from 7 to 5 ka. These new intervals of high carbon accumulation beg the question, where does this carbon come from? Why do we not see ice-core evidence for drawdown of atmospheric pCO2? For the answer, we look to the ocean. We find that during Holocene periods of high peat carbon accumulation, we also find increased upwelling in regions such as the Eastern Equatorial Pacific and the Southern Ocean, possibly providing the carbon that has been sinking in peatlands throughout the middle Holocene.